There are 6 diatomic molecules: H2, N2, O2, Cl2, F2, Br2 Calvin (K) scale has no negative # - there is an absolute zero – no energy level (Fo - 32)5/9 = Co Co +273 = Ko Graham’s Law Rate of diffusion is inversely proportional to the square root of their molar masses R1 = rate of diffusion of molecule A R2 = rate of diffusion of molecule B M1 = molar mass of A M2 = molar mass of B Avagadro’s Law: At STP the volume of 1 mole of any gas is 22.4L Mass Density = --------------Volume Example: H2 gas Mass – 2g 2g D = ------------ = 0.09g 22.4L The density of any gas is proportional to its molar mass D2 D1 Pressure A force applied to a certain object. One way to measure pressure is in pounds per square inch L/in2 or g/cm2. Pressure can also be measured in kilo-Pascals (100kPa = 5L/in2). Pressure can be measured in atm. At sea level air pressure is approx. 1atm. In most cases a manometer is used to measure pressure. A manometer is a Ushaped tube filled with mercury (has a very high density) when pressure is applied the Mercury moves away (up tube) from gas. The distance between the original end point of Hg and the endpoint after application of pressure, in millimeters of Hg equals the amount of pressure exerted. Open ended manometer – the pressure = deference in millimeters = 1atm Closed ended manometers are used to measure pressure that is significantly less that 1atm 1atm = 760 mmHg Another way of measuring pressure is to have a basin of mercury with a vertical tube sticking out and then to pour waster on both sides and measure how much mercury goes up tube. KE = 1/2 mv2 kinetic energy equals half mass times velocity squared V1 T2 velocity V2 T1 Boyle's Law - Temperature is constant – if pressure goes up volume goes down Charles' Law - Pressure is constant – if volume goes up temperature goes up or or Gay-Lussac's Law - volume is constant – if temperature goes up pressure goes up Combined Gas Law or STP standard temperature (0o C 273o K) and pressure (1atm) SATP standard atmospheric temperature (25o C 298o K) and pressure (1atm) Dalton's Law of Partial Pressures Partial pressure of each gas is proportional to the # of moles of that gas in the mixture. Ratio of Partial P to total P is equivalent to the ratio of the moles Example: 3mole O2, 1 mole H2O, 1mole CO2, 0.5mole N2 5.5 mole of that gas in this gas exerts the pressure of 1atm. How much pressure does each partial gas exert? O2 exerts x = 3/5.5 = 0.6atm H2O exerts x = 1/5.5 = 0.18atm CO2 exerts x = 1/5.5 = 0.18atm N2 exerts x = .5/5.5 = 0.9atm 101kPa = 1atm = 760mmHg 100kpa = 750mmHg Ideal Gas Equation (P-pressure, V-volume, n – # of moles, R – gas constant, T - temperature) Gas constant, R R = 0.0821 atm L / mol K if pressure is measured in atm OR R = 8.31 kPa L / mol K if pressure is measured in mmHg To find number of moles divide mass by molar mass mass/molar mass =n m mRT dRT dRT PV = --------RT P = --------- P = ------------ M = ------------ M MV M P Gas collected over water - Take the total pressure and subtract pressure of water at that temperature